www.sciencemag.org/content/363/6425/385/suppl/DC1

Supplementary Material for Design and control of gas diffusion process in a nanoporous soft crystal

Cheng Gu, Nobuhiko Hosono*, Jia-Jia Zheng, Yohei Sato, Shinpei Kusaka,

Shigeyoshi Sakaki, Susumu Kitagawa*

†Corresponding author. Email: nhosono@k.u-tokyo.ac.jp (N.H.); kitagawa@icems.kyoto-u.ac.jp (S.Ki.)

Published 25 January 2019, Science 363, 385 (2017) DOI: 10.1126/science.aar6833

This PDF file includes:

Materials and Methods Figs. S1 to S61 Tables S1 to S6 References

Other Supplementary Material for this manuscript includes the following: (available at www.sciencemag.org/content/363/6425/385/suppl/DC1)

Data Files S1 to S3

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Materials and Methods Materials

Tri-tert-butylphosphonium tetrafluoroborate (98%, TCI), 10H-phenothiazine (98%, TCI), palladium(II) acetate (98%, TCI), sodium tert-butoxide (98%, TCI), hydrogen peroxide (H2O2, 30 w/w, Wako), sodium hydroxide (97%, Nacalai), anhydrous dichloromethane (99.5%, Wako), anhydrous toluene (99.5%, Wako), anhydrous N,N-dimethylformamide (99.5%, Wako), anhydrous tetrahydrofuran (99.5%, Wako), anhydrous methanol (99.5%, Wako), 12 M HCl (Nacalai), copper(II) nitrate pentahydrate (99%, Aldrich), HKUST-1 (Aldrich), deuterated solvents for nuclear magnetic resonance (NMR) spectroscopy (Cambridge Isotope Laboratories) were purchased and used without further purification. Dimethyl 5-iodoisophthalate was prepared according to a literature procedure (27).

N2 (99.9999%), CO2 (99.9999%), H2 (99.9999%), O2 (99.9999%), Ar (99.9999%), CO (99.9999%), CH4 (99.9999%), C2H4 (99.9999%), C2H6 (99.9999%) and He (99.9999%) were purchased form TAIYO NIPPON SANSO Company (Japan). Synthesis of OPTz-ipa ligand

Synthesis of dimethyl 5-(10H-phenothiazin-10-yl)isophthalate (1): Dimethyl 5-iodoisophthalate (20.0 g, 62.5 mmol, 1.2 eq.), 10H-phenothiazine (10.4 g, 52.0 mmol, 1.0 eq.), tri-tert-butylphosphonium tetrafluoroborate (1.06 g, 3.64 mmol, 0.07 eq.), sodium tert-butoxide (7.50 g, 78.0 mmol, 1.5 eq.), palladium(II) acetate (584 mg, 2.60 mmol, 0.05 eq.) and toluene (400 mL) were placed in a flask whose inner gas was replaced by N2. The mixture was stirred at 80 °C for 16 h. After cooling down to room temperature, the reaction mixture was filtered through Celite®. The filtrate was diluted with AcOEt (200 mL) and washed with water. The organic phase was dried over Na2SO4, filtered and evaporated under reduced pressure. The residue was purified by column chromatography (SiO2, AcOEt/n-hexane with the ratio changing from 3 to 6%) to give 1 (11.4 g, yield = 56%) as a yellow solid. 1H NMR (400 MHz, CDCl3): δ (ppm) = 8.70 (1H, t, J = 1.4 Hz, phenyl (Ph) C2-H), 8.23 (2H, d, J = 1.4 Hz, Ph C4,6-H), 7.09-7.17 (2H, m, phenothiazine (PTz) C1,9-H), 6.87-6.98 (4H, m, PTz C2,3,7,8-H), 6.33-6.40 (2H, m, PTz C4,6-H), 3.95 (6H, s, -CO2CH3); 13C NMR (100 MHz, CDCl3): δ (ppm) = 165.60, 143.31, 142.74, 133.97, 133.22, 129.15, 127.47, 127.16, 123.70, 123.40, 118.15, 52.69; APCI-MS (positive mode): calcd. for [M+H]+, m/z = 391.09; found m/z = 391.02.

Synthesis of dimethyl 5-(5,5-dioxido-10H-phenothiazin-10-yl)isophthalate (2): 1 (8.26 g, 21.1 mmol, 1.0 eq.) was suspended in AcOH (83 mL) and H2O2 aqueous solution (30 w/w, 6.42 mL, 210 mmol, 10 eq.) was then added. The mixture was stirred at 80 °C for 3 h and then cooled to room temperature. Afterwards, the reaction mixture was charged with ice water (80 mL), neutralised with saturated NaHCO3 solution and extracted with CH2Cl2 (80 mL × 3). The organic phase was dried with Na2SO4, filtered and evaporated under reduced pressure. The residue was purified by flash column chromatography (SiO2, MeOH/CH2Cl2 = 2%) to give 2 (8.73 g, yield = 98%) as a white solid. 1H NMR (400 MHz, DMSO-d6): δ (ppm) = 8.72 (1H, t, J = 1.4 Hz, Ph C2-H), 8.29 (2H, d, J = 1.4 Hz, Ph C4,6-H), 8.09 (2H, dd, J = 7.8, 1.4 Hz, phenothiazine 5,5-dioxide (OPTz) C4,6-H), 7.54 (2H, dt, J = 8.7, 1.4 Hz, OPTz C2,8-H), 7.37 (2H, t, J = 7.8 Hz, OPTz C3,7-H), 6.66 (2H, d, J = 8.7 Hz, OPTz C1,9-H), 3.92 (6H, s, -CO2CH3); 13C NMR (100 MHz, DMSO-d6): δ = 164.23, 139.73, 139.19, 135.39, 133.62, 133.22, 130.44, 122.64, 122.57, 122.39, 117.16, 52.46; APCI-MS (positive mode): calcd. for [M+H]+, m/z = 423.08; found m/z = 423.00.

Synthesis of 5-(5,5-dioxido-10H-phenothiazin-10-yl)isophthalic acid (OPTz-ipa): 2 (12.0 g, 28.3 mmol) in THF (280 mL) was added 2 M NaOH aqueous solution (213 mL, 425 mmol) and the system was reflexed for 16 h. After cooling to 0 °C, the reaction mixture was acidified with concentrated HCl. The precipitate was collected by filtration, washed with water and then dried

3

under reduced pressure at 60 °C to give OPTz-ipa (11.5 g, yield = quant.) as a white solid. 1H NMR (400 MHz, DMSO-d6): δ (ppm) = 13.5-13.8 (2H, br, -CO2H), 8.72 (1H, t, J = 1.2 Hz, Ph C2-H), 8.20 (2H, d, J = 1.2 Hz, Ph C4,6-H), 8.09 (2H, dd, J = 7.9, 1.5 Hz, OPTz C4,6-H), 7.56 (2H, dt, J = 7.9, 1.5 Hz, OPTz C2,8-H), 7.38 (2H, t, J = 8.0 Hz, OPTz C3,7-H), 6.67 (2H, d, J = 8.0 Hz, OPTz C1,9-H); 13C NMR (100 MHz, DMSO-d6): δ = 165.41, 139.91, 139.00, 135.04, 134.90, 133.37, 130.94, 122.70, 122.64, 122.45, 117.30; APCI-MS (negative mode): calcd. for [M-H]-, m/z = 395.05; found m/z = 394.01.

Synthesis of Cu(OPTz)

Firstly, 500 mg (1.26 mmol) OPTz-ipa was dissolved in 50 mL DMF at room temperature. An aqueous solution (50 mL) of Cu(NO3)2·5H2O (700 mg, 2.52 mmol) was added to the above solution. Then the mixture was heated at 80 °C for 24 h. The Cu(OPTz) was obtained as blue needle-like crystals with the length up to several centimetres (510 mg, yield = 72%). The crystals were filtered, washed with DMF (50 mL, 3 times) and methanol (50 mL, 1 time) and dried in air. The as-synthesised Cu(OPTz) was characterised by infrared spectra (fig. S13). The adsorption peak of the stretching vibration of C=O double bond shifted to low wavenumber, indicative of the coordination bonds formation in the PCP.

Solvent exchange and activation of Cu(OPTz)

In order to measure the gas adsorption property of the Cu(OPTz), we exchanged the guest and coordination solvents (DMF and water) with methanol by soaking Cu(OPTz) into methanol at 60 °C for 3 days. Every 24 h the methanol was replaced by new one. After exchange, the PCP was dried under vacuum at 60 °C for 3 h. 1H NMR confirmed that all the guest and coordination solvents were completely exchanged by methanol (fig. S15).

TGA curve showed that the framework of the exchanged Cu(OPTz) was thermally stable until 320 °C, whereas at 50 °C the PCP lost all the guest solvents (fig. S16). Thus we activated the PCP at 120 °C for 11 h to afford 1a; this temperature ensured complete removal of the guest solvents meanwhile excluded the possibility of framework decomposition. Before measuring the gas adsorption, 1a was activated again in-situ on BELmax or BEL18 gas sorption apparatuses at 120 °C for 2 h.

General instrumental analysis

1H and 13C NMR spectra were recorded at 25 °C or 60 °C on a JEOL RESONANCE model ECS-400, operating at 400 and 100 MHz, respectively, where chemical shifts (δ in ppm) were determined with respect to tetramethylsilane (TMS) as an internal reference. Atmospheric pressure chemical ionization (APCI) mass spectra were recorded on a Bruker model micrOTOF II.

Infrared spectra were measured on a JASCO model FT/IR-4700 Fourier transform infrared spectrometer. Thermogravimetric analysis (TGA) was performed on a Rigaku Thermo plus EVO2 under a N2 atmosphere with a temperature ramp of 5 °C min−1. Differential scanning calorimetry (DSC) was recorded on a DSC 3500 Sirius calorimeter (NETZSCH co.).

X-ray diffraction

Single-crystal X-ray diffraction (SXRD) measurements were performed on a Rigaku XtaLAB P200 diffractometer equipped with a Dectoris PILATUS 200 K detector, using a VariMax Mo Optic with Mo−Kα radiation (λ = 0.71075 Å). The structure was solved using direct methods and refined by full-matrix least-squares cycles in SHELX 2014/7 (28). All non-hydrogen atoms were refined using anisotropic thermal parameters.

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Powder X-ray diffraction (PXRD) measurements were performed on a Rigaku SmartLab X-ray diffractometer using Cu−Kα radiation (λ = 1.54178 Å) in the 2θ range of 3−40° with a scanning rate of 5° min−1.

Gas sorption and in-situ PXRD measurements

Gas sorption measurements were performed on BELSORP-max and BELSORP-18PLUS (MicrotracBEL, Japan, Corp.) automated volumetric sorption analysers, equipped with cryostatic temperature controllers.

The in-situ PXRD/adsorption measurements were carried out using a Rigaku SmartLab with Cu−Kα radiation connected to BELSORP-18PLUS volumetric adsorption equipment. Those apparatuses were synchronised with each other and each PXRD pattern was obtained at each point of the sorption isotherms or isobars.

Structural analysis of activated and C2H4-adsorbed PCPs

The PXRD data for the structural analyses of 1a were collected using a synchrotron X-ray and multiple PILATUS 100K detectors of the BL5S2 beam line at Aichi Synchrotron Radiation Center (29). The PXRD data for the structural analyses of the C2H4-adsorbed 1a were collected using a synchrotron X-ray and multiple MYTHEN detectors of the BL02B2 beam line at Super Photon ring (SPring-8) (30, 31). The crystalline powder of 1a in a silica glass capillary (0.4 mm inside diameter) was heated at 393 K in vacuum for 1 h to remove the guest molecules. The sample for the structural analysis of 1a was sealed in vacuum and that for the C2H4-adsorbed 1a was filled with C2H4 (80 kPa) at 77 K and sealed. The latter sample was kept at room temperature for three days in order to let 1a adsorb C2H4. The measurement temperature was changed from 370 to 180 K at the cooling rate of 10 K min–1 with nitrogen flow.

The Rietveld analysis (32) for activated and C2H4 adsorbed phases of 1a was carried out. Before structural refinement, indexing for these phases was performed with Conograph software (33). Initial structural model of C2H4 adsorbed phase was constructed by using the structure of activated phase. The positions of adsorbed C2H4 molecules were estimated with maximum entropy method (MEM) (34, 35). Final structures of activated and C2H4 adsorbed phase for 1a were obtained with reliability factors RB (based on Bragg intensity) and Rwp (based on whole pattern) of 0.09663 and 0.02281 for activated phase, 0.07604 and 0.04531 for adsorbed phase, respectively (table S2).

For the structural refinement of the adsorbed phase, the simulated structure that was generated and optimised by Monte-Carlo and DFT method (fig. S35), respectively, was used as the initial geometry.

Isosteric heat of adsorption

The binding energy of C2H4 is reflected in the isosteric heat of adsorption, Qst, defined as

(1)

The calculations are based on the use of the Clausius-Clapeyron equation.

Quantification of the diffusion rate The diffusion rate was measured on a BELSORP-max (BEL Japan, Inc.) automated

volumetric sorption analysers and was fitted automatically with BEL-Dyna software according to the Crank theory (36) described as follows:

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5

Adsorption rate equation in consideration of in-particle diffusion (assuming spherical particle):

(2)

When boundary condition r = R, q = q0n Linear equilibrium equation:

(3) Batch adsorption operating equation:

(4) where

Ds: surface diffusion coefficient [cm2 s-1] H: equilibrium constant [cm3 g-1] P: pressure [Pa] P0: initial pressure [Pa] Pe: equilibrium pressure [Pa] q: adsorbed amount [cm3 g-1] q0: initial adsorption amount [cm3 g-1] R: radius of particle [cm] t: time [s] V: gas phase volume [cm3] W: adsorbent amount [g] By solving simultaneous equations of the above (2), (3) and (4), the following solution is

obtained:

(5)

Equation (5) is called Crank equation.

(6)

Providing that P = CRT, equation (5) is as follows:

(7)

where

,

For the adsorption rate analysis program, equation (7) is used. The diffusion rate was simultaneously measured with every plot in the adsorption isotherms,

and was quantified in the temperature range of 250 to 370 K. In the case of 170 to 240 K, the accurate fitting by Crank theory was difficult because of the low diffusion rate in this temperature range.

Theoretical simulation

The isobar measurement of adsorption suggested that 15 molecules of C2H4 were adsorbed into 1a for one unit cell at the saturated limitation (fig. S27). To seek the adsorption positions of these C2H4 molecules, we carried out canonical Monte-Carlo (MC) simulations (37), using the standard universal force field (UFF) (38) to describe the Van der Waals interaction between C2H4 and 1a framework and that between C2H4 molecules. The electrostatic interaction was evaluated with the Ewald summation method, where atomic charges were calculated using the charge equilibration method (39). The initial geometry of 1a with adsorbed C2H4 molecules was constructed by placing 60 C2H4 molecules (corresponding to 15 C2H4 molecules per one unit cell)

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in a simulation box of 2×1×2 supercell of 1a. In the MC simulation, the first 1×107 steps were consumed for obtaining equilibration and then 2×107 steps calculation was performed for seeking the best adsorption position. In the final configuration, the positions of C2H4 molecules can be divided into two groups, suggesting that there are two possible sites, namely sites I and II, for C2H4 adsorption in 1a. Considering the symmetry of 1a, each of these two sites contains 8 C2H4, which corresponds to 16 C2H4 molecules in one unit cell. These two sites were considered in further density functional theory (DFT) calculations, where the initial geometry was generated from the final configuration of the above MC simulation by considering the symmetry to reduce the computational cost.

The adsorption energy was calculated using spin-polarised DFT method with periodic boundary conditions as implemented in the Vienna Ab initio Simulation Package (VASP 5.4.1)

(40, 41). The Perdew-Burke-Ernzerhof functional (42) with Grimme’s semiempirical “D3” dispersion term (43) (PBE-D3) was employed in these calculations. Plane wave basis sets with an energy cutoff of 500 eV were used to describe valence electrons, while core electrons were described by the projector-augmented-wave pseudopotentials (44, 45). The Brillouin zone was sampled by a Γ-point. During the geometry optimisation, both cell parameters and atomic positions were fully optimised until all atomic forces become smaller than 0.01 eV/Å. A Hubbard U correction (46) with the U value of 4.0 eV (47) was applied to the localised d electrons of Cu2+ center.

The adsorption energy (Eads) of C2H4 into 1a was calculated with equation (8): (8)

where is the total energy of 1a with n molecules of C2H4 per unit cell, and are the total energies of empty 1a and one free C2H4 molecule, respectively. The SCS-MP2 correction was made to the adsorption energy calculated by equation (8), using cluster models shown in fig. S35. In these cluster models, the dangling bonds were capped with H atoms. The resolution of identity (RI) approximation (48) was employed in SCS-MP2 calculations, as implemented in the GAMESS program (49). Dunning’s correlation-consistent aug-cc-pVDZ basis sets (50, 51), where the diffuse functions of H were removed, were used with appropriate auxiliary basis functions (52, 53) for RI approximations. Basis set superposition error (BSSE) was corrected using the counterpoise method (54). The final adsorption energy was calculated with equation (9):

(9) where and are interaction energies of ethylene molecule with cluster models (i =1 and 2 for sites I and II, respectively), calculated by the SCS-MP2 and PBE-D3 methods.

The climbing-image nudged elastic band (CI-NEB) method (55) was used to evaluate the diffusion barrier of C2H4 in 1a at different loading with 1, 7, and 15 C2H4 molecules, respectively. Three diffusion pathways were considered, i.e., intra-caged, intra-layered, and inter-layered diffusions, which correspond to the C2H4 transfer from position 1 to 2, from 3 to 4, and from 4 to 5, respectively, as shown in Fig. 3C. In these calculations, the convergence criterion for geometry optimisation was chosen to be 0.03 eV/Å to save computational time. In the calculations of C2H4 diffusion in half and fully adsorbed phases, we only considered the process where one C2H4 molecule was allowed to change its position from one cage to the neighbour one, whereas other C2H4 molecules were kept within the same cage. For convenience, we denoted these two types of C2H4 molecules as “diffusing” and “non-diffusing” C2H4.

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7

The energy barriers for the rotation and flipping of OPTz ring in a free OPTz-ipa ligand were calculated using Gaussian 09 program (56). Geometry optimisations and vibrational frequency calculations were carried out using DFT method with the dispersion-corrected (43) B3LYP functional (B3LYP-D3). The 6-311G(d,p) basis sets were used for all atoms, where a set of diffuse functions was added to O atoms. The rotation barrier was estimated by scanning the potential energy surface (PES), in which one dihedral angle (C1N1C2C3, fig. S11) was changed with an interval of 5°.

Gas separation experiments by temperature-swing adsorption (TSA) protocol

The steps below were carried out similar to steps reported previously (57, 58). 1. Pre-treatment:

The powder sample of 1a was set on a cryostat system and heated to 393 K under vacuum condition (below 10-2 Pa) for 11 h. 2. Adsorption process:

In the O2/Ar separation, the temperature was decreased from 393 to 180 K under vacuum. Then once the temperature reached to 180 K, a mixed gas of O2 and Ar (volume ratios controlled by mass flow controllers, flow rate at 5 mL min-1) was flowing at ambient pressure, and the temperature was kept at 180 K for a certain period under flowing mixed gas.

In the C2H4/C2H6 separation, the temperature was decreased from 393 to 270 K under vacuum. Then once the temperature reached to 270 K, a mixed gas of C2H4 and C2H6 (volume ratios controlled by mass flow controllers, flow rate at 5 mL min-1) was flowing at ambient pressure, and the temperature was kept at 270 K for 1 h under flowing mixed gas. 3. Flowing away the non-adsorbed gas:

The remained gas in the chamber and gas lines was flowed away by He with a flow rate of 12 mL s-1 for 30 s. 4. Release and detection of the adsorbed gas:

After the He flow, the sample chamber was closed and the temperature increased to 393 K for releasing the adsorbed gas. The released gas was examined with gas chromatography and the ratio between O2 and Ar (or C2H4 and C2H6) was evaluated from the chromatogram. Gas chromatography equipment (GC-2014; SHIMADZU) with either a capillary or packed column was used to analyse the released gas. For O2/Ar analysis, a capillary column (Rt-Msieve 5A, ID: 0.53 mm, L: 30 m, Restek) was used and the column temperature was kept constant at –15 °C during the measurements by a thermostatic bath. For C2H4/C2H6 analysis, a custom-made Al2O3 column (ID: 3 mm, L: 1m) was used and the column temperature was kept at 100 °C during the measurements.

The separation factor a is defined as (taking O2/Ar as example): a = (XO2/YO2)/(XAr/YAr) = (XO2/XAr)/(YO2/YAr) (10)

where: XO2 = the concentration of O2 in the adsorbed phase YO2 = the concentration of O2 in the feed gas XAr = the concentration of Ar in the adsorbed phase YAr = the concentration of Ar in the feed gas.

Mixed-gas adsorption measurements

Mixed-gas sorption measurements on 1a were performed on BELSORP-VC (MicrotracBEL, Japan, Corp.). A mixed feed gas (C2H4/C2H6 = 1/1, V/V, 2 bar in total pressure) was prepared and

8

introduced into the sample cell at 298 K. The adsorption amount was determined by the total pressure change after gas dosing time (1, 2, 8, 24, and 48 hours) and composition ratio that was determined by 490 Micro GC System (Agilent Technologies, Inc.). Because of the regulated diffusion rate at 298 K, the adsorption amount and selectivity were varied as a function of gas dosing time. Temperature-programmed desorption (TPD) experiments

The TPD experiments on 1a was carried out as following steps using BEL-CAT II (MicrotracBEL, Japan, Corp.). All experimental steps were performed at atmospheric pressure. 1. Sample loading and activation:

1a (0.66 g) was filled in the cylindrical cell (8 mmf) and activated at 393 K in vacuum for 10 hours. The sample cell was then placed on BEL-CAT II. 2. Gas dosing step:

The sample was dosed with C2H4 at constant flow of 15 sccm for 1 hour at 393K. Subsequently, the sample temperature was ramped at a rate of –0.8 K/min to 298 K and held at 298 K for 1 hour in the flowing C2H4 (15 sccm). 3. Gas releasing step:

The flowing gas was switched to He (15 sccm) at 298 K, where encapsulated C2H4 was slowly released under exposure to He and swept away to be detected by a thermal conductivity detector (TCD) placed after the sample cell. He was used for the reference gas of TCD. The sample was kept at this condition for (A) min with monitoring the TCD signal that corresponds to the amount of released C2H4. 4. Desorption step:

After the releasing time of (A) min, temperature of sample cell was elevated to 393 K at a rate of 6.3 K/min and kept at 393 K for 2 hours to evacuate all C2H4 encapsulated in 1a. In this step, all encapsulated C2H4 was released to give a peak in the TCD data.

The steps 2-4 were repeated with an increment of releasing (He exposure) time, (A) = 60,

120, 240, and 360 min. The TPD experiment was also carried out using H2 instead of C2H4 using exactly same

temperature program in order to obtain a baseline data. Because H2 uptake of 1a at 298 K is negligibly low, we used TPD data of H2 as the baseline that corresponds to the amount of free gas presenting at inter-particle cavities and/or any dead spaces in the cell/pipelines.

The amount of released C2H4 was calculated by integrating area of TCD signal after the baseline subtraction. The relative amount of encapsulated C2H4 at given releasing time (60, 120, 240, or 360 min) was calculated as (integration area of TCD peak at step 4) / (whole integration area of TCD data at step 3-4).

The control experiment using HKUST-1 (0.45 g) was carried out in the same protocol.

9

Supplementary Figures

Fig. S1 Synthetic route of OPTz-ipa.

10

Fig. S2 1H NMR spectra of 1.

11

Fig. S3 13C NMR spectra of 1.

12

Fig. S4 APCI mass spectra of 1.

13

Fig. S5 1H NMR spectra of 2.

14

Fig. S6 13C NMR spectra of 2.

15

Fig. S7 APCI mass spectra of 2.

16

Fig. S8 1H NMR spectra of OPTz-ipa.

17

Fig. S9 13C NMR spectra of OPTz-ipa.

18

Fig. S10 APCI mass spectra of OPTz-ipa.

19

Fig. S11 Potential energy surface for the rotation of OPTz ring in a free ligand molecule.

20

Fig. S12 Photos of as-synthesised Cu(OPTz) (A) in vial and (B) under microscope. Needle-like blue crystals with the length up to several centimetres were formed, indicative of high crystallinity of Cu(OPTz).

21

Fig. S13 Infrared spectra of the OPTz-ipa ligand and as-synthesised Cu(OPTz).

22

Fig. S14 Single-crystal structure of as-synthesised Cu(OPTz). (A) Cu2+ paddle-wheel linked with OPTz ligands. (B), (C) and (D) represent the view of the crystal structure along a-, b- and c-axis, respectively. C: grey; N: blue; S: yellow; O: red; Cu: sky blue. Hydrogen atoms are omitted for clarity. In the as-synthesised Cu(OPTz), the Cu2+ and the ligands form Cu2+ paddle-wheel units, the axial positions of which are occupied by water molecules. The linkage of paddle-wheel units and ligands gives rise to a typical square lattice (SQL)-type two-dimensional sheet structure.

23

Fig. S15 1H NMR of the PCP samples dissolved in DMSO-d6 containing deuterium chloride. The PCP samples were destroyed by deuterium chloride (2~3 drops) in DMSO-d6. The black and red curves represented the as-synthesised and exchanged PCPs, respectively. The peaks pointed by green arrows were the peaks of OPTz-ipa ligand, whereas the peaks pointed by pink and blue arrows were the peaks of DMF and methanol, respectively. The NMR clearly showed that the DMF in the PCP was completely exchanged by methanol after solvent exchange.

24

Fig. S16 TG curves of the as-synthesised (black line) and exchanged (red line) PCPs. In the case of as-synthesised Cu(OPTz), the two weight loss steps corresponded to the loss of water (100 to 150 °C) and DMF (230 to 300 °C), respectively. As for the exchanged Cu(OPTz), the weight loss at 30 to 50 °C corresponded to the loss of methanol. The exchanged Cu(OPTz) was thermally stable until 340 °C.

25

Fig. S17 (A) Experimental and simulated PXRD patterns of the as-synthesised Cu(OPTz) and 1a. (B) Enlarged 2θ range of 5 to 12.5 degree showing the low-intensity peak corresponding to (020) facet in 1a. The PXRD pattern of 1a was different with the as-synthesised one, indicating a structural transformation during the activation.

26

Fig. S18 PXRD patterns of 1a soaked in diverse solvents at different temperatures for a period of time, or left in air at room temperature for 4 months. 1a exhibited outstanding stability upon soaking in methanol at 60 °C for seven days, or leaving in ambient atmosphere for 4 months. As a contrast, 1a soaked in water gradually transformed back to the as-synthesised phase, as revealed by their consistent PXRD patterns. 1a could not retain its crystallinity when soaked in DMF at room temperature for 1 day.

27

Fig. S19 Rietveld analysis result of the synchrotron PXRD patterns of the activated PCP 1a. Crystallographic information file (CIF) of the result is attached as data S2.

5 10 15 20 25 30 35 40

0

1x103

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28

Fig. S20 Gas adsorption isotherm measurements of 1a: (A) CO2 at 194.7 K; (B) N2 at 77.35 K; (C) CO at 82 K; (D) C2H6 at 184.6 K; (E) CH4 at 195 K; (F) O2 at 90.2 K. CO2 is an exception of this adsorption behaviour because it caused a structural transformation of the framework (fig. S34). Thus, CO2 was excluded from the following discussions.

29

Fig. S21 Gas adsorption isobar curves of CO2, CH4, N2, CO and H2. The isobar measurements were conducted from low to high temperature. Note that the starting temperatures were ca. 10 K higher than the Tbp of the gases. This parameter setting prevented the condensation of the gases on the surface of 1a. CO2 is an exception of this adsorption behaviour because it caused a structural transformation of the framework (fig. S34). Thus, CO2 was excluded from the following discussions.

30

Fig. S22 Gas adsorption isotherm measurements of C2H4 at diverse temperatures: (A) 170 to 190 K; (B) 200 to 220 K; (C) 230 to 250 K; (D) 260 to 280 K; (E) 290 to 310 K; (F) 320 to 340 K; (G) 350 to 370 K.

31

Fig. S23 (A) Crystal lattice parameters and (B) cell volume of 1a under vacuum at diverse temperatures. As an indication of the relatively “rigid” nature of the framework, the unit cell parameters of 1a only showed negligible change in various temperatures. Lattice parameter changed anisotropically; a- and c-axes increased whereas b-axis decreased during heating. The cell volume only increased by 47.4 Å3 (from 4161.6 to 4209 Å3) as increasing the temperature. The negligible change of the cell parameters at diverse temperatures ruled out the possibility of thermal-induced structural expansion.

32

Fig. S24 Differential scanning calorimetry (DSC) curves of 1a in the temperature range from 173 to 393 K. No obvious endothermic and exothermic peaks were observed from the DSC curves, excluding the presence of the thermal-induced crystallographic phase transition.

!!

MM!!

':$%I'6G>!S020*',/F!4'+*!Ow0*T!F$,_'0!F+&F$&+*'C!1,2(!3N;b!+C02,%*/2)!+*!MJU!+)C!M[U!AE!K4'!w0*!_+&$'! B+0! F+&F$&+*'C! *2! 9'! N[E[! :=! (2&>"7! B4/F4! B+0! )2*! +0! 4/54! +0! *4+*! 21! F&+00/F! '*4-&')'!+C02,%*/2)!c3c0!O$8T7!B4/F4!*-%/F+&&-!042B'C!*4'!w0*!_+&$'0!21!(2,'!*4+)!bU!:=!(2&>"E!K4/0!,'0$&*!/)C/F+*'C!*4+*!*4'!5+0>1,+('B2,:!+11/)/*-!/0!(2C',+*'!,+*4',!*4+)!4/54!/)!*4/0!0-0*'(!+)C!F2$&C!)2*!9'!*4'!,'+02)!21!*4/0!5+0!+C02,%*/2)!9'4+_/2$,E!

34

Fig. S26 C2H4 adsorption isotherms for 1a at 200 K using different exposure time. We measured the C2H4 adsorption isotherms at 200 K with the exposure time of each plot as 300 s, 1200 s and 3600 s, respectively, resulted in a total measurement time of 17.5, 67.0 and 234.2 h, respectively. The adsorption amount markedly increased with the prolonged exposure time, which importantly indicated that the diffusion kinetics of adsorbates was the determining factor for this thermoresponsive adsorption behaviour.

35

Fig. S27 C2H4 and C2H6 adsorption isobars measured at different temperature directions of (A) 180 K → 370 K → 180 K for C2H4 and 200 K → 370 K → 200 K for C2H6, and (B) 370 K → 180 K → 360 K for C2H4 and 370 K → 200 K → 360 K for C2H6. When the C2H4 and C2H6 adsorption isobars were measured in the temperature direction of 180 K → 370 K → 180 K, the adsorption amount continuously increased to 92 mL g-1 as the temperature decreased to 180 K. Conversely, when the temperature direction was 370 K → 180 K → 370 K, the two isobar curves were perfectly superimposable with each other and obeyed the thermodynamic law. Additionally, the curve of maximum adsorption amounts measured from the isotherms matched impeccably with the isobar curve measured by increasing the temperature. These results suggested that the initial condition of the adsorption is the key to determine the adsorption behaviour. At low temperature, the diffusion was initially impeded and gradually boosted as increasing the temperature, leading to a temperature-assisted adsorption. On the contrary, the diffusion barrier is expected to be lower if the initial framework was at high temperature. After adsorbing gases the diffusion barrier is further decreased. As a result 1a exhibited ordinary adsorption behaviour. These results clearly show a self-promoted adsorption process, in which the pre-adsorbed gas molecules facilitate subsequent adsorption.

36

Fig. S28 The relationship of temperature and maximum C2H4 adsorption amounts measured by isobar (temperature from 180 to 370 K) and isotherms.

37

Fig. S29 C2H4 adsorption amounts at 1 bar for 1a at 200 and 320 K using different exposure time. At low temperature of 200 K, the adsorption amount slightly increased with the exposure time, and then gradually became constant. Even using extremely long exposure time of ca. 24 h for each plot, which was the machine limitation of our adsorption measurement equipment, the adsorption amount could not increase to ca. 90 mL g-1 as achieved in the isobar measurement by decreasing the temperature. These results demonstrated that the assistance of temperature is critically important.

38

Fig. S30 In-situ PXRD/adsorption measurements of 1a. (A) C2H4 adsorption isotherm at 320 K. (B) PXRD patterns measured at each point shown in the C2H4 adsorption isotherm.

39

Fig. S31 In-situ PXRD/adsorption measurements of 1a. (A) C2H6 adsorption isotherm at 320 K. (B) PXRD patterns measured at each point shown in the C2H6 adsorption isotherm.

40

Fig. S32 Variable-temperature PXRD of 1a under vacuum condition in the temperature range from 180 to 370 K.

!!

b"!!

!:$%I' 6JJ! #F4'(+*/F! C/+5,+(! 21! *4'! '11'F*0! 21! *4'! XcKV! 1&/%%/)5! 2)! *4'! F,-0*+&! 0*,$F*$,'E!32)1/5$,+*/2)!21!*4'!XcKV>/%+!B/*4!C/11',')*!%4')-&OXcKVTv%4')-&OXcKVT!C/4'C,+&!+)5&'0!21!O]T!"[Ue!O*',('C!+0!y0*+*/FzT!+)C! OpT!"bQe! O*',('C!+0!y1&/%%/)5zT7! ,'0%'F*/_'&-E!^)/*>F'&&! 0*,$F*$,'!21!A(!$)C',! O3T! y0*+*/Fz! +)C! OLT! y1&/%%/)5z! 0*+*$07! ,'0%'F*/_'&-E! K4'! XcKV! ,/)5! /)! (+5')*+! F2&2$,!042B'C!*4'!F+5'!+%',*$,'!2)!O"""T!1+F'*!O0:->9&$'!%&+)'TE!K4'!F4+)5'!21!F+5'!+%',*$,'!21!A(!$)C',!OgT!y0*+*/Fz!+)C!OIT!y1&/%%/)5z!0*+*$07!,'0%'F*/_'&-E!K4'!,'C!+,,2B!/)C/F+*'0!*4'!F+5'!+%',*$,'!12,!/)*',>&+-','C!C/11$0/2)E!K2!F&'+,&-!042B!*4'!'11'F*0!21!*4'!XcKV!1&/%%/)5!2)!*4'!F,-0*+&!0*,$F*$,'7!B'!(+)$+&&-!F4+)5'C!*4'!%4')-&OXcKVTv%4')-&OXcKVT!C/4'C,+&!+)5&'0!2)!*4'!XcKV!,/)5!1,2(!"[Ue!*2!"bQe7!B4/&'! :'%*! 2*4',! %+,*0! 21! *4'! F,-0*+&! 0*,$F*$,'! 0+('! +0! *4'! /)/*/+&! 0*,$F*$,'E! S)! *4'0'! *B2!0*,$F*$,'07!*4'!0*,$F*$,'!21!*4'!1,+('B2,:!F2)0*,$F*'C!B/*4!3$Nl!%+CC&'>B4''&0!+)C!/02%4*4+&+*'0!:'%*!*4'!0+('7!B4','+0!*4'!XcKV!(2/'*/'0!042B'C!)'+,>%&+)+,!+)C!*B/0*'C!5'2('*,-7!,'0%'F*/_'&-E!K4$0!*4'!*B2!0*,$F*$,'0!F2$&C!0*+)C!12,!*4'!)2)>1&/%%/)5!O0*+*/FT!+)C!1&/%%/)5!(2C'0!21!A(!+*!&2B!+)C!4/54!*'(%',+*$,'7!,'0%'F*/_'&-E!K4'!y1&/%%/)5z!0*,$F*$,'!,'_'+&'C!+!0&/54*!'W%+)0/2)!21!k"""m!

42

axis compared to the “static” structure, in good agreement with the VT-PXRD results that the peaks corresponding to (111) facet shifted to low angle. Since OPTz moiety is oriented parallel to the (111) plane, this tiny expansion of [111] distances could be correlated with an extent of thermal flipping of the OPTz moiety. Notably, the “flipping” structure showed a remarkable enlargement of cage aperture for inter-layered diffusion compared to the “static” structure, which indicated that the “flipping” structure allowed accelerating the gas diffusion in response to increasing temperature.

43

Fig. S34 In-situ PXRD/adsorption measurements of 1a. (A) CO2 adsorption isotherm at 195 K. (B) PXRD patterns measured at each point shown in the CO2 adsorption isotherm. In contrast with other gases that could not cause the structural transformation of 1a framework, The PXRD patterns of CO2 adsorption isotherm at 195 K showed a shrink on (002) and (102) facets and a decrement in intensity of the peak corresponding to the (131) facet.

44

Fig. S35 (A) Optimised crystal structure of 1a with adsorbed C2H4 molecules at two different sites, each of which has an occupancy of 8 (i.e. 16 molecules per unit cell). Cluster models used in SCS-MP2 calculations for (B) site I and (C) site II. The golden and green models represent the C2H4 molecules docking at site I and II, respectively. The number of C2H4 molecules in the fully adsorbed phase well corresponded to the isobar results (15 molecules / unit cell, fig. S27).

45

Fig. S36 Rietveld analysis result of the synchrotron PXRD patterns of 1a in C2H4-adsorbed phase. Crystallographic information file (CIF) of the result is attached as data S3.

5 10 15 20 25 30 35 40 45 50

0

1x105

2x105

3x105

Pbcaa = 12.9343(3) Å, b = 24.1082(9) Å, c = 13.4335(3) ÅRwp = 4.53%, RI = 7.06%

Yobs Ycalc Ybg peak bar Yobs-Ycalc

2q (deg.)

Inte

nsity

(cou

nts)

-30000

0

30000

Yobs

-Yca

lc

46

Fig. S37 Calculated intra-caged C2H4 diffusion energy of 1a.

47

Fig. S38 (A) Reaction coordinate–energy plot used to determine the intra-layer diffusion energies for the activated (black line), half-adsorbed (site I, blue line) and fully adsorbed (red line) states of 1a (73.4, 77.1, and 49.3 kJ mol–1, respectively). (B) Calculated intra-layer diffusion rates of 1a under activated phase, half adsorbed phase (site I) and fully adsorbed phase. The diffusion rates are calculated by the Arrhenius equation D/D0 = exp(–Ea/RT), where Ea is the diffusion barrier.

48

Fig. S39 (A) Reaction coordinate–energy plot used to determine the inter-layer diffusion energies for the activated (black line), half-adsorbed (site I, blue line) and fully adsorbed (red line) states of 1a (102.3, 115.9, and 105.6 kJ mol–1, respectively). (B) Calculated inter-layer diffusion rates of 1a under activated phase, half adsorbed phase (site I) and fully adsorbed phase. The diffusion rates are calculated by the Arrhenius equation D/D0 = exp(–Ea/RT), where Ea is the diffusion barrier.

49

Fig. S40 Flow path diagram of TSA gas separation experiment for the process (A) No. 1, (B) No. 2, (C) No. 3 and 4, (D) No. 5, (E) No. 6, 7 and 8.

Note: Experimental procedure for gas separation with flow diagrams: No. 1. Activating the sample in the cell in vacuum at 393 K for 11 h (A). No. 2. Mixed gas flowing at 180 K (O2/Ar) or 270 K (C2H4/C2H6) (B). No. 3. Closing the valves of V3 and V4 (C). No. 4. Evacuation of remained gas in the gas line (Area 3, C). No. 5. Flowing away remained gas in the sample chamber with He flush (D). No. 6. Closing the valves of V3 and V4 (E). No. 7. Heating to 393 K to desorb gas from the sample. No. 8. GC test.

50

Fig. S41 Gas chromatograms for gas mixtures of O2 and Ar. (A) A 50.0/50.0 mixture of O2 and Ar before adsorption. (B) – (F) Adsorbed gases on 1a in 100 kPa of a mixed gas atmosphere (O2/Ar = 50.0/50.0) with the exposure time of 24 h, 8 h, 4 h, 2 h and 1 h, respectively.

!!

\"!!

!!

:$%I'6KG!32,,'&+*/2)!21!5+0!C20/)5!*/('!+)C!0'%+,+*/2)!1+F*2,!12,!A(E!]!_+&$'!21!0'%+,+*/2)!1+F*2,!&+,5',!*4+)!$)/*-!('+)0!*4+*!*4'!(+*',/+&!%,'1',')*/+&&-!+C02,90!XN!(2&'F$&'0E!XN!/0!%,'1',')*/+&&-!+C02,9'C!2)!A(!2_',!+!B/C'!,+)5'!21!'W%20$,'!*/('E!

52

Fig. S43 Gas chromatograms for gas mixtures of O2 and Ar. (A) A 39.4/60.6 mixture of O2 and Ar before adsorption. (B) Adsorbed gases on 1a in 100 kPa of a mixed gas atmosphere (O2/Ar = 39.4/60.6) with the exposure time of 1 h.

53

Fig. S44 Gas chromatograms for gas mixtures of O2 and Ar. (A) A 29.3/70.7 mixture of O2 and Ar before adsorption. (B) Adsorbed gases on 1a in 100 kPa of a mixed gas atmosphere (O2/Ar = 29.3/70.7) with the exposure time of 1 h.

54

Fig. S45 Gas chromatograms for gas mixtures of O2 and Ar. (A) A 19.8/80.2 mixture of O2 and Ar before adsorption. (B) Adsorbed gases on 1a in 100 kPa of a mixed gas atmosphere (O2/Ar = 19.8/80.2) with the exposure time of 1 h.

55

Fig. S46 Gas chromatograms for gas mixtures of O2 and Ar. (A) A 9.7/90.3 mixture of O2 and Ar before adsorption. (B) Adsorbed gases on 1a in 100 kPa of a mixed gas atmosphere (O2/Ar = 9.7/90.3) with the exposure time of 1 h.

56

Fig. S47 Gas chromatograms for gas mixtures of O2 and Ar. (A) A 4.9/95.1 mixture of O2 and Ar before adsorption. (B) Adsorbed gases on 1a in 100 kPa of a mixed gas atmosphere (O2/Ar = 4.9/95.1) with the exposure time of 1 h.

57

Fig. S48 Gas chromatograms for gas mixtures of O2 and Ar. (A) A 59.1/40.9 mixture of O2 and Ar before adsorption. (B) Adsorbed gases on 1a in 100 kPa of a mixed gas atmosphere (O2/Ar = 59.1/40.9) with the exposure time of 1 h.

58

Fig. S49 Gas chromatograms for gas mixtures of O2 and Ar. (A) A 69.2/30.8 mixture of O2 and Ar before adsorption. (B) Adsorbed gases on 1a in 100 kPa of a mixed gas atmosphere (O2/Ar = 69.2/30.8) with the exposure time of 1 h.

59

Fig. S50 Gas chromatograms for gas mixtures of O2 and Ar. (A) A 79.9/20.1 mixture of O2 and Ar before adsorption. (B) Adsorbed gases 1a in 100 kPa of a mixed gas atmosphere (O2/Ar = 79.9/20.1) with the exposure time of 1 h.

60

Fig. S51 Gas chromatograms for gas mixtures of C2H4 and C2H6. (A) A 4.9/95.1 mixture of C2H4 and C2H6 before adsorption. (B) Adsorbed gases on 1a in 100 kPa of a mixed gas atmosphere (C2H4/C2H6 = 4.9/95.1) with the exposure time of 1 h.

61

Fig. S52 Gas chromatograms for gas mixtures of C2H4 and C2H6. (A) A 10.5/89.5 mixture of C2H4 and C2H6 before adsorption. (B) Adsorbed gases on 1a in 100 kPa of a mixed gas atmosphere (C2H4/C2H6 = 10.5/89.5) with the exposure time of 1 h.

62

Fig. S53 Gas chromatograms for gas mixtures of C2H4 and C2H6. (A) A 19.5/80.5 mixture of C2H4 and C2H6 before adsorption. (B) Adsorbed gases on 1a in 100 kPa of a mixed gas atmosphere (C2H4/C2H6 = 19.5/80.5) with the exposure time of 1 h.

63

Fig. S54 Gas chromatograms for gas mixtures of C2H4 and C2H6. (A) A 30.3/69.7 mixture of C2H4 and C2H6 before adsorption. (B) Adsorbed gases on 1a in 100 kPa of a mixed gas atmosphere (C2H4/C2H6 = 30.3/69.7) with the exposure time of 1 h.

64

Fig. S55 Gas chromatograms for gas mixtures of C2H4 and C2H6. (A) A 39.3/60.7 mixture of C2H4 and C2H6 before adsorption. (B) Adsorbed gases on 1a in 100 kPa of a mixed gas atmosphere (C2H4/C2H6 = 39.3/60.7) with the exposure time of 1 h.

65

Fig. S56 Gas chromatograms for gas mixtures of C2H4 and C2H6. (A) A 50:50 mixture of C2H4 and C2H6 before adsorption. (B) Adsorbed gases on 1a in 100 kPa of a mixed gas atmosphere (C2H4/C2H6 = 50.0/50.0) with the exposure time of 1 h.

66

Fig. S57 Gas chromatograms for gas mixtures of C2H4 and C2H6. (A) A 59.8/40.2 mixture of C2H4 and C2H6 before adsorption. (B) Adsorbed gases on 1a in 100 kPa of a mixed gas atmosphere (C2H4/C2H6 = 59.8/40.2) with the exposure time of 1 h.

67

Fig. S58 Gas chromatograms for gas mixtures of C2H4 and C2H6. (A) A 69.7/30.3 mixture of C2H4 and C2H6 before adsorption. (B) Adsorbed gases on 1a in 100 kPa of a mixed gas atmosphere (C2H4/C2H6 = 69.7/30.3) with the exposure time of 1 h.

68

Fig. S59 Gas chromatograms for gas mixtures of C2H4 and C2H6. (A) A 80.4/19.6 mixture of C2H4 and C2H6 before adsorption. (B) Adsorbed gases on 1a in 100 kPa of a mixed gas atmosphere (C2H4/C2H6 = 80.4/19.6) with the exposure time of 1 h.

!!

JP!!

!!!!

!!!

:$%I'6LB!`'0$&*0!21!(/W'C>5+0!+C02,%*/2)!'W%',/(')*0!2)!A(!('+0$,'C!+*!NPQ!A!B/*4!3N;bi3N;J!h!"i"7!qYq!O*2*+&!%,'00$,'!h!N!9+,TE!K4'!+C02,9'C!+(2$)*!21!'+F4!5+0!+)C!0'%+,+*/2)!1+F*2,!+,'!%&2**'C!+0!+!1$)F*/2)!21!5+0!C20/)5!*/('E!! !

!!

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:$%I'6LA!`'0$&*0!21!KcL!'W%',/(')*0E!O]T!A(!+)C!OpT!;A^#K>"E!K4'!KcL!C+*+!042B0!K3L!0/5)+&!/)*')0/*-!*4+*!F2,,'0%2)C0!*2!*4'!,'&'+0'C!3N;b!+(2$)*!+*!0*'%!M!+)C!b!O5+0!,'&'+0/)5!+)C!C'02,%*/2)!0*'%7!,'0%'F*/_'&-T!+*!NPQ!A!O#''!.+*',/+&0!+)C!.'*42C0!0'F*/2)TE!K4'!3N;b!*,+%%'C!/)0/C'!A(!B+0!0&2B&-!,'&'+0'C!/)!*4'!;'!1&2B!+*!NPQ!A!+*!"!9+,E!K4'!,'&'+0'C!5+0!B+0!(2)/*2,'C!9-!K3L7!B4/F4!042B'C!+)!'W%2)')*/+&>&/:'!C'F+-!/)!*4'!9'5/))/)5!21!,'&'+0/)5!*/('!O0*'%!MTE!]1*',!,'&'+0/)5!*/('!21!JU!O,'CT7!"NU!O2,+)5'T7!NbU!O5,'')T7!+)C!MJU!(/)!O9&$'T7!*4'!0+(%&'!B+0!4'+*'C!$%!*2!MPM!A!B4','! +&&! 3N;b! ')F+%0$&+*'C! /)! A(! B+0! C'02,9'C7! &'+_/)5! +! K3L! 0/5)+&! %'+:! O0*'%! bTE! ]&&!'W%',/(')*+&!%,2F'C$,'0!+,'!C'*+/&'C!/)!.+*',/+&0!+)C!.'*42C0!0'F*/2)E!K4'!%'+:!+,'+!+)+&-0/0!042B'C!*4+*!bPEbR!21!3N;b!/0!,'*+/)'C!/)!A(!+1*',!MJU!(/)!$)C',!;'!1&2BE!I2,!;A^#K>"7!/*!B+0!12$)C!*4+*!2)&-!bEbR!21!3N;b!/0!,'*+/)'C!+1*',!JU!(/)!/)!*4'!0+('!F2)C/*/2)E!!

71

Supplementary Tables Table S1. Crystallographic data and structural refinement summary for as-synthesised Cu(OPTz).

as-synthesised Cu(OPTz) crystal system monoclinic space group P21/c (#14)

empirical formula C23H22CuN2O9S a (Å) 15.1908(4) b (Å) 12.1616(2) c (Å) 14.5275(5) α (o) 90 β (o) 117.786(4) γ (o) 90

V (Å3) 2374.41(13) Z, dcalcd (g cm-3) 4, 1.583 diffractometer CCD

μ (cm−1) 1.065 radiation type Mo Kα

radiation wavelength (Å) 0.71075 F(000) 1164

goodness of fit 1.007 temperature (K) 103

number of reflections collected/unique 6511/6185 Rint 0.0122

R1 (I > 2.00σ(I))[a] 0.0265 wR2 (I > 2.00σ(I))[b] 0.0776

[a]R1 = Σ||Fo|-|Fc||/Σ|Fo|, [b]wR2 = [Σw|Fo2-Fc2|2/Σw(Fo2)2]1/2

72

Table S2. Crystallographic data and Rietveld refinement summary for 1a and C2H4-adsorbed 1a.

1a C2H4-adsorbed 1a crystal system orthorhombic orthorhombic space group Pbca (#61) Pbca (#61)

a (Å) 12.9647(8) 12.9345(3) b (Å) 24.1436(3) 24.1072(9) c (Å) 13.4068(5) 13.4333(3) α (o) 90 90 β (o) 90 90 γ (o) 90 90

V (Å3) 4196.5(7) 4188.7(2) diffractometer Debye-Scherrer Debye-Scherrer radiation type synchrotron synchrotron

radiation wavelength (Å) 0.799640(2) 0.999680(2) temperature (K) 180 180

RB[a] 0.09663 0.06926 Rwp[b] 0.02281 0.04505

[a]RB = Σ|Io–Ic|/ΣIo, [b]Rwp = [Σw|yo–yc|2/Σwyo2]1/2.

73

Table S3. Summary of kinetic diametres, Tmax, Tbp and ΔT of various gases.

gas kinetic

diameter (59) (Å)

Tmax (K)

Tbp (K)

ΔT = Tmax–Tbp (K)

H2 2.83 120 20.25 99.75 O2 3.47 200 90.2 109.8 Ar 3.54 250 87.35 162.65 N2 3.64 250 77.35 172.65 CO 3.69 250 82 168 CH4 3.76 300 111.6 188.4 C2H4 4.16 320 169.5 150.5 C2H6 4.44 370 184.6 185.4

74

Table S4. Theoretically optimised unit cell parameters and adsorption energies of C2H4 at different sites.

site a (Å) b (Å) c (Å) V (Å3) (kJ mol-1)

(kJ mol-1)

0 12.83 (12.96)

24.40 (24.14)

13.42 (13.41)

4202.7 (4196.6)[a] – –

I 12.66 24.44 13.45 4162.7 –45.3 –27.8 (–27.7)[b] II 13.01 24.41 13.16 4179.0 –45.9 –31.4 (–27.7)[b]

[a]Experimental values are shown in parentheses. [b]Experimental heats of adsorption (-Qst).

PBE-D3adsE SCS-MP2:PBE-D3

adsE

75

Table S5. Various energy terms (kJ mol-1) for C2H4 diffusion at different phases.[a]

Phase Initial State (IS) Transition State (TS)

( )[b]

Activated –45.0 – –12.3 – 40.3 – Half

Adsorbed –47.3

(–44.6)[c] –274.3 (–45.7) –13.4 –277.3

(–46.2) 43.1 45.4

Fully Adsorbed

–47.1 (–40.4)[c]

–573.7 (–41.0) –23.1 –588.8

(–42.1) 25.2 39.0 [a] and represent interaction energies of the diffusing C2H4 and other C2H4 molecules with the 1a framework, respectively. and are the deformation energy of the empty 1a framework and that of 1a with other C2H4 molecules. These energy terms were calculated by equations (11) – (14):

(11)

(12)

(13)

(14) where and are total energies of 1a with n+1 and n C2H4 molecules (n = 0, 6 and 14 for the activated, half and fully adsorbed phases, respectively) at the initial and transition states,

is total energy of one C2H4 molecule. [b] and represent total interaction energies of other C2H4 molecules with 1a framework and the average values, respectively. [c]The interaction energies between the diffusing C2H4 and 1a without and with other C2H4 molecules are shown in and out parentheses, respectively.

The diffusion barrier was determined by the energy difference between initial and transition states during the diffusion process. Therefore, the interaction energies of C2H4 with the 1a framework at the initial and transition states and the deformation energy of framework from initial to transition states are main factors for diffusion barrier. For convenience, we denote the C2H4 molecule transferring from one cage to another one as “diffusing C2H4” and remaining ones as “non-diffusing C2H4” in the discussion. As shown in Table S5, the interaction of the diffusing C2H4 molecule with framework becomes weaker as the adsorption amount increases. This is reasonable because the C2H4 molecule takes the best adsorption position at the low loading stage but cannot at the high loading in the congested situation to weaken the interaction. However, non-diffusing C2H4 molecules form some weakly attractive interactions with the diffusing C2H4 at the high loading stage, which moderately suppress the movement of the diffusing C2H4, as shown in Table S5. As a result, the overall interaction of the diffusing C2H4 with the 1a framework (and non-diffusing C2H4 molecules) at the initial state in the fully adsorbed phase is similar to that in the activated one. On the other hand, Table S5 shows that the deformation energy of framework (with or without non-diffusing C2H4 molecules) from the initial and transition states becomes smaller at the high loading stage, contributing to the smaller diffusion barrier. To understand this result, we separately calculated the deformation energy of the empty 1a framework and that of 1a

1defE 2

defE1INT (IS)E

2INT (IS)E

2INT (IS) >E<

1INT (TS)E

2INT (TS)E2INT (TS) >E<

1INTE 2

INTE1defE 2

defE

424242 HCHCa1HC1)(a11INT EEEE nn --= ×+×

424242 HCHC0a1HCa12INT nEEEE n --= ××

2 4 2 4

1def 1a 0C H 1a 0C H(TS) (IS)E E E× ×= -

2 4 2 4

2def 1a C H 1a C H(TS) (IS)nnE E E× ×= -

42HC1)(a1 +× nE42HCa1 nE ×

2 4C HE2INTE 2

INTE< >

76

with non-diffusing C2H4 molecules, as shown in Table S5. As expected, the deformation energy of the empty 1a framework ( ) is similar among all three cases (activated, half adsorbed, and fully adsorbed cases) because of their similar structural changes during the C2H4 diffusion passing through the cage window. However, the overall deformation energy is much smaller in the fully adsorbed phase than that in the activated one. These results suggest that for the fully adsorbed case, non-diffusing C2H4 molecules interact with the 1a framework more strongly in the transition state than in the initial one, as evidenced by the calculated interaction energies ( ) shown in Table S5. The larger interaction energy of non-diffusing C2H4 molecules at the transition state can be explained as follows: if the diffusing C2H4 leave its adsorption position in one cage to diffuse into another one, then non-diffusing C2H4 molecules could accordingly tune their adsorption positions to interact better with the 1a framework, leading to the larger interaction energy. Such increased interaction between non-diffusing C2H4 molecules and the 1a framework compensate the deformation energy of the 1a framework at the transition state. However, such interaction is absent in the case of C2H4 diffusion in the activated phase, which increases the diffusion barrier. We also noted that the interaction of diffusing C2H4 with the 1a framework becomes stronger as the C2H4 loading increases, probably because of the attractive interactions with non-diffusing C2H4 molecules, which stabilises the transition state and decreases the diffusion barrier. Based on the above results, it is likely concluded that the smaller diffusion barrier at higher loading phase mainly arises from the suppression of deformation energy at the transition state due to the presence of non-diffusing C2H4 molecules in the framework.

1defE

2defE

2INTE

77

Table S6. Structures and physicochemical properties of O2, Ar, C2H4 and C2H6 (59).

O2 Ar C2H4 C2H6

kinetic diameter (Å) 3.47 3.54 4.16 4.44

standard boiling point (K) 90.2 87.35 169.5 184.6 critical temperature (K) 154.58 150.86 282.34 305.32 critical pressure (bar) 50.43 48.98 50.41 48.72

critical volume (cm3 mol-1) 73.37 74.57 131.10 145.50 Polarizability (×1025 cm-3) 15.812 16.411 42.52 44.3

78

Crystallographic Data S1.

Crystallographic information file (CIF) of the as-synthesized PCP (1).

CCDC number: 1879452

Crystallographic Data S2.

Crystallographic information file (CIF) of the activated PCP (1a).

CCDC number: 1879451

Crystallographic Data S3.

Crystallographic information file (CIF) of the C2H4-adsorbed phase of 1a (1a-C2H4).

CCDC number: 1879450

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